Gestational Age Calculator

Your details

Choose whichever date you know best. Each method resolves to the same standard timeline.
The first day of bleeding in your most recent period, not the day it ended. This is the standard reference obstetricians use.
Standard dating assumes 28 days. Longer or shorter cycles shift ovulation, so the due date is adjusted by (cycle - 28) days.
days
Leave blank to use today. Set a past or future date to see gestational age on that day.
Gestational ageThird trimester
36 wk 1 d
Current trimesterThird trimester
Completed weeks36wk
Total days of gestation253days
Fetal age (since conception)34 wk 1 d
Progress to due date90%
Estimated conception dateJanuary 15, 2026
Estimated due dateOctober 8, 2026
Days until due date27days
36 wk
  • Second trimester
  • Viability
  • Third trimester
  • Full term
  • Due date
  • Post-term

36 wk 1 d pregnant, third trimester.

  • You are in the third trimester at 36 wk 1 d of gestation. Fetal age (counted from conception) is about 34 wk 1 d.
  • About 27 days remain until the estimated due date of October 8, 2026 (40 weeks), and you are roughly 90% of the way there.
  • The estimated conception date is January 15, 2026. LMP dating assumes ovulation about two weeks after the last period, so an early ultrasound may shift these dates.

Next stepConfirm dating with your prenatal provider; a first-trimester ultrasound is the most accurate way to set your due date.

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